It is recognized that some form of surface treatment alternative is desired to attain the maximum service life of these asphalt pavements. Alternate methods such as precoated aggregate, slurry seals, fog seals over chip seals, and a variety of other methods need to be considered. The different variables involved with chipseals (aggregates, binders, construction, etc.), as well as alternatives to chip seals need to be researched for possible improvements.
Research is needed to determine what modifications to our current chip sealing practices are necessary to eliminate future occurrences of this type or to suggest alternative technologies, such as slurry seals or open-graded friction courses, which can substitute while still achieving the benefits of a successful chip seal.
Findings: The South Dakota DOT has made extensive use of chip seal and sand seal surface treatments in the maintenance of their AC pavements. Such surface treatments have been found to provide a cost-effective means of extending the life of AC pavements in South Dakota. Although the use of chip seals and sand seals have for the most part been reliable treatments, there have been some notable failures, especially on high-volume, high-speed roadways. This project was undertaken to investigate the use of chip seals for such applications and to make recommendations to improve their performance. This project also involved the development of guidelines for the design and construction of chip seals.
To evaluate the use of chip seals in South Dakota, several efforts were undertaken. First, an extensive literature review was conducted to develop an understanding of the latest practices and experiences. Second, interviews were conducted with South Dakota DOT from all departments involved in the chip seal process to investigate their practices and to determine areas for improvement. Finally, test sections were constructed to evaluate the performance of standard and modified chip seal designs. The test sections consisted of 12 chip seal designs and included two aggregate types (quartzite and natural aggregate) and alternate chip seal designs with new gradations and other modifications and enhancements. Based on these efforts, recommendations are provided to improve chip seal performance. In addition, guidelines were developed to select feasible surface treatments for a specific project.